The present invention relates generally to illumination devices, such as night lights for example. More particularly, the present invention relates to illumination devices including apparatuses for automatically deactivating or deenergizing the lights when the immediate ambient temperature exceeds a predetermined temperature level.
A wide variety of night lights and other illumination devices are well-known in the prior art. In one common type of night light contruction, the light bulb is energized only when the night light is plugged into an electrical outlet receptacle and thus remains illuminated until the night light is removed from the receptacle. In another very common night light construction, a manually-actuable switch is provided so that the light bulb can be selectively energized or deenergized while the night light is still electrically connected to an electrical outlet receptacle. Frequently, in still another common type of night light, the manual switch is replaced by a light sensitive switch that automatically energizes the light bulb in response to a predetermined low ambient light condition and deenergizes the light bulb in response to a predetermined high ambient light level. An example of such an automatic, light sensitive night light device is disclosed and described in U.S. Pat. No. 3,968,355, issued July 6, 1976. Such U.S. patent is assigned to the same assignee as that of the present invention, and its disclosure is hereby incorporated by reference herein.
In accordance with the present invention, any of the various types of night lights or other illumination devices described above are provided with a feature for automatically deactivating or deenergizing the night light bulb when the temperature of the immediately surrounding environment exceeds a predetermined temperature level. The present invention provides such a feature in a construction that is relatively inexpensive to manufacture and produce and that does not detract from the appearance of the night light device. The present invention further provides such a heat deactivating feature in a construction that allows the heat sensitive component or components of the night light device to be positioned for optimum, expedient detection of the immediately surrounding ambient temperature level.
In order to achieve the objectives mentioned above, an illumination device according to the present invention generally includes a housing, electrical plug prongs, a connector portion associated with the housing for receiving and electrically contacting a light bulb, and a heat sensitive electrical circuit for conducting electrical current from an electrical outlet or other electrical power source to a light bulb received within through the connector portion of the illumination device. Preferably, the heat sensitive electrical circuit includes a bimetallic strip or other heat sensitive mechanism that automatically interrupts the flow of electrical current through the connector portion of the night light when the temperature sensed by the bimetallic strip exceeds a predetermined temperature level. In this embodiment, the bimetallic strip simultaneously can also function as a current conductor, a heat sensor, and an electrical switch, and can also be located out of view in the housing of the illumination device.
In another embodiment of the present invention, an illumination device is equipped with a successive heat sensitive switching mechanism, in which the power conducted to the light bulb is initially reduced in response to ambient temperature levels exceeding a first predetermined temperature level, with the flow of electrical current to the light bulb being interrupted only in response to a second, higher predetermined temperature level.